Our data indicates that insulin B chain amino acids 9 to 23 peptide (insulin B:9-23) may be a primary target essential for the initiation of spontaneous diabetes in NOD mice and that T cells recognizing this peptide have a T cell receptor that specifically shares conserved Valpha and Jalpha segments. I will define using transplants, the specific timing and location of the contribution of insulin B:9-23 in the development of islet autoimmunity. I will also directly test the hypothesis that genomically encoded T cell receptor chains are crucial for disease in the NOD mouse and for recognition by the T cell repertoire of the insulin B:9-23 peptide. I propose to create NOD mice having the presumed "irrelevant" single Jalpha 56 segment, which has different sequence from the conserved Jalpha segment (53/42), and to evaluate them for development of anti-islet autoimmunity. C57BL/6 mice bearing only Jalpha 56 were established where a single Jalpha is used to create the immune repertoire, and we will create congenic Jalpha 56 NOD mice using speed congenic techniques. I predict if the Jalpha 53/42 conserved sequences are critical, anti-insulin/islet autoimmunity will not develop for NOD mice having only the "irrelevant" Jalpha 56 sequence. If prevention occurs in mice with the single Jalpha 56, we will molecularly create mice with the single Jalpha 56 sequence modified to be a Jalpha 53 sequence, and I predict restoration of autoimmunity. For the independent phase, I will define sequences of the conserved alpha chain that confer anti-insulin autoimmunity with novel molecular retrogenic techniques. Producing retrogenic mice with the original and modified alpha chain T cell receptors will allow us to define crucial sequences. We will molecularly transfer amino acid cassettes from the conserved Valpha and Jalpha of anti-B:9-23 diabetogenic clones into a "irrelevant" control alpha chain to assess whether we can create anti-insulin autoimmunity, and will transfer amino acid cassettes from control alpha chain into anti-B:9-23 diabetogenic alpha chains to suppress or abrogate autoimmunity. If this pathway is critical in the NOD mouse, it will stimulate a search for an analogous human critical pathway. As a long-term goal, plans are included to first develop methodology in the mouse model and eventually apply similar retrogenic and molecular techniques to T cell receptors of man from pancreatic islet infiltration of man.